I've had a similar problem with my heavy weight karate Gi. After much threading and rethreading (it wasn't a quick or easy-ish job either) I managed to get the drawstrings back to length, but to be honest it was alot less hassle to buy a new one.

Some guys at my BJJ school remove the drawstring that comes with the gi and replace it with a thin gauge nylon rope. I think it's mountain climbing rope, as long as you don't mind a brightly colored bule or whatever color drawstring you won't have to deal with uneven drawstrings again.

Interesting note, my new Padilla and Sons GI comes with a "rope" drawstring that resembles the rope other guys use to replace their shitty cotton drawstrings. Just another reason why my Padilla an Sons Gi is the best Gi ever. I wish it were socially acceptable and cool to wear a GI for every occasion.

I've never tried elastic waitsband dogi bottoms, but always wondered if they were a good idea.

...I usually take my drawstring out of my pants before I throw them in the wash....it helps prevent them from disappearing. Of course you are going to have to rethread it everytime you wash it (unless you wash it by hand). Then you can always rethread the drawstring using a clothes hanger, or something.

Really? I never have that problem. Mind you I use a front-loader, it's a lot gentler on things than the top-load, but even on the old top-loader I never lost a string. Total justification for the insane price I pay for my judogi, I reckon.